The processes involved in the fabrication and packaging of circuit chips are well known. Typically, an array of identical circuits is patterned onto a circular semiconductor wafer using well known microlithographic techniques. The wafer is then sawed into many rectangular pieces to separate the individual circuits from one another, so that each circuit occupies its own circuit chip.
The chips are individually mounted onto lead frames, where they are held in place by means of an epoxy. A wire bonder is then used to establish electrical connections between the die pads on the chip and the respective leads of the lead frame.
With the chip physically and electrically attached to the lead frame, the chip and lead frame are placed into a mold equipment, where plastic is transfer molded to surround the assembly. This plastic packaging serves to protect the chip exposure to light, moisture and contamination, which could damage the circuit components, as well as making the entire assembly mechanically rigid and durable. The molded plastic is then cured by means of heating in an oven for several hours.
The leads of the lead frame are then trimmed and formed into the desired shape. For example, the leads may be formed into a “gull wing” shape for surface-mounted chips. At this stage, various electrical and mechanical tests are performed to determine whether the chip will function for its intended purpose.
The circuit chip industry is very cost-competitive. It is therefore desirable to shorten, streamline or eliminate packaging steps to shorten production time and reduce production costs for the chips.